Several studies have brought up job insecurity as an increasingly serious problem in organisations (De Witte, 1999; Greenhalgh and Rosenblatt, 1984; Kinnunen, Mauno, Natti and Happonen, 1999; Sverke and Hellgren, 2002). The growing number of studies on job insecurity can, to a great extent, be attributed to the increase in situations where job insecurity experiences are prevalent, such as periods of downsizing or restructuring (Burke and Nelson, 1998; Hellgren and Sverke, 2001; Hitt, Keats, Harback and Nixon, 1994). Definitions of job insecurity emphasise the subjective experience of a threat to the continuation of one's employment (Greenhalgh and Rosenblatt, 1984; Hartley, Jacobson, Klandermans, and van Vuuren, 1991; De Witte and Näswall, 2003). Job insecurity has also been described as a violation of the psychological contract the employee feels has been established between her or him and the employer, which guarantees continued employment if one works well (King, 2000). The increasing knowledge of job insecurity and psychological contract violations attributes impaired well-being and negative attitudes toward the organisation to the fear of job loss (Ashford, Lee and Bobko, 1989; Barling and Kelloway, 1996; Hartley et al., 1991). There is also evidence of negative consequences for the organisation where there is uncertainty, in that the employees react to job insecurity by taking different actions. In this chapter we focus on three forms of such actions described by Hirschman (1970) as exit, voice, and loyalty reactions to unsatisfactory situations. According to this framework, employees may exit from the organisation, use their voice by protesting against the organisational change, or express loyalty to the organisation in order to restore security in the future.